Reciprocating fluid motor

ABSTRACT

A reciprocating fluid motor has a piston shiftably carried in a bore of a longitudinally extending housing having end closure portions at each end of the bore and each having a secondary bore of reduced size therethrough. The piston has elongated shaft portion extending from ends thereof with said shift having a reduced diameter area adjacent said piston with the shaft portions being slidable in the secondary bores and having at least one end thereof projecting from the housing and adapted for attachment to mechanism requiring reciprocable drive. A freely slidable valve is positioned in the bore and shiftable by fluid pressure to alternately admit fluid pressure to opposite sides of the piston to shift same in respective opposite directions. Recesses in an exterior surface of the valve receives fluid from a respective fluid intake passage to create an imbalance of pressure on opposite ends of the valve and of a magnitude sufficient to effect shifting of the valve upon movement of the piston adjacent each end of its path of reciprocation in a respective direction.

United States Patent 1 3,853,036

Eskridge et a]. Dec. 10, 1974 RECIPROCATING FLUID MOTOR Primary ExaminerPaul L. Maslousky [76] lnvemors: wade Eskridge 907 Ashbury Attorney, Agent, or Firm-Fishburn, Gold & Litman Rd., Olathe, Kans. 66061; Duane 0. Kennedy, 353 N. 31st St., Kansas City, Kans. 66100 [57] ABSTRACT [22] Filed: Aug 20 1973 A reciprocating fluid motor has a piston shiftably carried in a bore of a longitudinally extending housing [21] Appl' 389,448 having end closure portions at each end of the bore Related Application Data and each having a secondary bore of reduced size therethrough. The piston has elongated shaft portion extending from ends thereof with said shift having a reduced diameter area adjacent said piston with the [63] Continuation-impart of Ser. No. 278,561, Aug. 7,

i972. abandoned.

52 us. or 91/276, 91/319, 91/317 Shaft Porticms being Slidable the Secondary bores 51 Int. Cl. F0ll 17/00, FOll 25/02 and having One end hereof Pmiecting from 58 Field of Search 91/276, 319, 317 hwsmg and adapted for attachment to mechanism requiring reciprocable drive. A freely slidable valve is [56] References Cited positioned in the bore and shiftable by fluid pressure to alternately admit fluid pressure to opposite sides of UNITED STATES PATENTS the piston to shift same in respective opposite direc- 1907395 10/1911 Lane 9l/276 tions. Recesses in an exterior surface of the valve re 11399223 12/192 91/276 ceives fluid from a respective fluid intake passage to g igggjg Ehrislensen create an imbalance of pressure on opposite ends of 3592l09 7/197 I276 the valve and of a magnitude sufficient to effect shift- 3 643 548 2/1972 Butterwo rthiii.................::.:: 91/319 Ofthe Valve movement Oflhe Piston adjacent each end of its path of reciprocation in a respective FOREIGN PATENTS 0R APPLICATIONS direction. 1,213,692 3/1966 Germany 91/319 10 Claims, 10 Drawing Figures 2 54 4 I8 35 6 l v /;7 W7? 7 4 V V v V I /f// I 1 0M, i 2 v A g a. 30 7 28, 29 i k u 7 29 V W? w e 1* 29' 29 as r M e w e e 2e" a W J 1 3e jg I I 1' ll 27 az zfils l 16 57 26 L27 PAIENIED [155 1 SHEEI 30F 4 RECIPROCATING FLUID MOTOR This is a continuation-in-part of application Ser. No. 278,561, filed Aug. 7, 1972, now abandoned.

The present invention relates to reciprocating fluid motors and more particularly to an improved reciprocating fluid driven motor of the type adapted to drive units, such as reciprocating mower blades, pavement breakers, saws, hammers, or other devices which operate with a reciprocating motion and particularly to a fluid motor that is useful as a drive means for such units.

The principal objects of the present invention are: to provide a reciprocating fluid motor having a fluid pressure actuated, fluid control sleeve valve constructed in a novel mananer so as to avoid the necessity of providing mechanical devices to urge the piston thereof past a dead center position and which also functions to maintain the valve in one control position or the other driving reciprocation of the piston; to provide such a reciprocating fluid motor having a piston reciprocably mounted in a motor housing along with a movable sleeve valve surrounding the piston and shiftable by fluid pressure as the piston approaches respective opposite ends of its path of travel to cause pressurized fluid which has been introduced into recesses in an exterior surface of the sleeve valve to effect movement of the sleeve valve upon movement of the piston adjacent respective opposite ends of its path of reciprocation; to provide such a reciprocating fluid motor adapted to have fluid pressure effect starting of the piston and shifting of the valve member particularly after the piston and sleeve valve have stopped in their extreme positions toward one end of its stroke; to provide such a reciprocating fluid motor having end closure members and means therein for permitting communication of fluid trapped between the piston and respective end closure member with an outlet passage to thereby permit the piston to complete its stroke; to provide such a reciprocating fluid motor adapted to prevent hydrostatic locking of the piston wherein inlet and outlet ports are provided in the sleeve valve and are positioned in spaced relationship such that a source of pressurized fluid as well as outlet or exhaust passages are both necessarily brought into momentary simultaneous communication with the motor housing on both sides of the piston when the sleeve valve is intermediate the ends of its path of movement; to provide such a reciprocating fluid motor wherein ends of a sleeve valve are movable into interfitting relationship with end closure members when the piston approaches respective opposite ends of its path of reciprocating movement and flow passages communicating fluid between the piston and the end of the sleeve valve so that increased pressure of fluid effects the shifting of the sleeve valve toward an intermediate dual fluid communication position and which then operates to maintain a pressure imbalance on the piston and sleeve valve and of a magnitude and in a direction to assure continued movement of the piston in its initial direction until the sleeve valve has been shifted to its other fluid control location; to provide such a reciprocating fluid motor adapted to momentarily trap fluid adjacent respective ends of travel of the piston and ends of the sleeve valve to thereby serve as a cushion and prevent chattering of the valve during initial movement thereof particularly when the reciprocating fluid motor is operated at relatively high rate of reciprocation; and to provide such a reciprocating fluid motor which is positive in operation, durable in construction, economical to manufacture, simple to service, and particularly well adapted for the proposed use.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features of the reciprocating fluid motor.

FIG. 1 is a longitudinal sectional view of a reciprocating fluid motor embodying features of the present invention and showing a piston intermediate the ends of a bore.

FIG. 2 is a longitudinal sectional view showing the piston adjacent an end of one stroke and closing outlet ports in a valve member.

FIG. 3 is a longitudinal sectional view showing the piston adjacent one end of its stroke and prior to movement of a valve member.

FIG. 4 is a longitudinal sectional view showing the piston at one end of its stroke and showing the valve member moved to effect movement of the piston in an opposite direction.

FIG. 5 is a transverse sectional view taken on line 5-5, FIG. 1 and showing flow passages through an end closure member.

FIG. 6 is a transverse sectional view taken on line 6-6, FIG. 1 and showing outlet ports of a valve member communicating with an outlet passage.

FIG. 7 is a transverse sectional view taken on line 7-7, FIG. 2 and showing the piston closing the outlet ports of the valve member.

FIG. 8 is an enlarged fragmentary longitudinal sectional view showing flow passages through an end closure member and a fluid receiving slot adjacent and communicating with an inlet port of the valve member.

FIG. 9 is a longitudinal sectional view of a modified reciprocating fluid motor showing the piston adjacent one end of one stroke and closing outlet ports in a valve member.

FIG. 10 is a longitudinal sectional view of a modified reciprocating fluid motor and is similar to FIG. 9 except showing the piston intermediate the ends of a bore.

Referring more in detail to the drawings:

As required, detailed embodiments of the present invention are disclosed herein, however, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate detailed structure.

In the disclosed embodiment of the present invention, the reference numeral 1 generally designates a reciprocating fluid motor which has a piston 2 shiftably carried in a bore 3 of a longitudinally extending housing 4 having end closure portions 5 and 6 at respective opposite ends of the bore 3 and with the end closure portions 5 and 6 having secondary bores 7 and 8 respectively of reduced size therethrough. The piston 2 is on an elongated shaft 9 or has shaft portions extending therefrom in opposed relation, and is positioned intermediate the ends of a section 10 of reduced diameter with the shaft 9 being slidably received in the secondary bores 7 and 8 and having at least one end thereof projecting from the housing 4 and adapted for attachment to mechanism requiring reciprocable drive. A freely slidable valve member 11 is positioned in the bore 3 and is shaftable by fluid pressure to alternately admit fluid pressure to opposite sides of the piston 2 thereby shifting same in opposite directions. Recesses in an exterior surface of the valve member 11 receive fluid from a fluid intake passage 12 to create an imbalance of pressure on opposite ends of the valve member 11 and of a magnitude sufficient to effect shifting of the valve member 11 upon movement of the piston 2 adjacent each end of its path of reciprocation in a respective direction.

The housing 4 may have any desired exterior shape, however, the illustrated housing 4 is generally cylindrical and has substantially opposed inlet and outlet bosses l4 and respectively, each internally threaded to receive a suitable fluid conduit (not shown). The inlet boss 14 communicates with the fluid intake passage 12 and the outlet boss 15 receives fluid from an outlet fluid passage 16 which is illustrated as being on an opposite side of the housing 4 from the intake passage l2. The end closure portions 5 and 6 are suitably mounted on the housing 4, as later described, and have facing surfaces to define limits of the stroke of the piston 2.

The housing 4 has inlet ports 17 and 18 at the ends of the bore and the inlet ports 17 and 18 communicate with annular passages 19 and 20 respectively in the surface defining the bore 3. The housing 4 also has spaced outlet ports 21 and 22 communicating with annular passages 23 and 24 respectively which are adjacent the annular passages 19 and 20.

Small or restricted flow passages 25 and 26 communicate respective opposite ends of the outlet fluid passage 16 with the portion of the bore closed by the end closure portions 5 and 6 respectively, for a purpose as later described.

The end closure members 5 and 6 are each illustrated as having a flange portion 27 engageable with respective opposite ends of the housing 4 and the end closure portions 5 and 6 each have a projecting portion 28 extending from the flange portion 27 and into respective ends of the bore 3. The projecting portions 28 each have an end portion 29 of reduced diameter thereby defining a recess between the bore 3 of the housing 4 and the surface of the respective end portion 29. The recesses so formed are each adapted to receive respective ends of the valve member H, as later described.

Each end portion 29 has an annular groove or recess 28 near the end face 29' thereof. The respective groove 28' communicates through passages 28" to the secondary bores 7 when section 10 of the shaft 9 passes into the respective secondary bore 7, the shaft 9 closing said passages 28" when the respective sections 10 are in the bore 3. It is preferred that the passages 28 be two or more in number and of a size relative to the flow passages 25 and 26 that the total flow capacity of the passages 28" be in the nature of 2 to l to the total flow capacity of the flow passage 25 or 26 at the respective end of the housing. This provides for pressure at the end of a piston stroke to start shifting of the valve member 11.

A plurality of circumferentially spaced flow passages 30 extend radially through the end portions 29 of the end closure portions 5 and 6 and provide communication between the secondary bores 7 and 8 and the recess defined by the exterior surface of the end portions 29 and the interior surface of the bore 3. The flow passages 30 through the end closure portions 5 and 6 permit fluid to flow from the space between the secondary bore through the respective end closure portion and the section 10 of reduced diameter of the shaft 9 and a restricted or partial flow into the respective flow passages 25 and 26 for flow into the outlet fluid passage l6 when the piston 2 closes the respective outlet ports 21 and 22 and the annular passages 23 and 24 as later described.

The shaft 9 is illustrated as an elongated member reciprocable in the bore 3 and in the secondary bores 7 and 8. The shaft 9 has the section 10 of reduced diame ter intermediate the ends thereof with respective portions of the section 10 of reduced diameter movable into the secondary bores 7 and 8 at the respective ends of the strokes of the piston 2.

The ports 30 and passages 28" of one end portion 29 are closed by the shaft 9 in the respective secondary bore 7 when the piston 2 at or near the other end of its stroke. Then as the piston reverses and moves toward said one end portion the ports 30 and passages 28" remain closed until the leading edge of the adjacent reduced section l0 enters the respective secondary bore 7 as said leading edge passes the inner end of the passages 28" and then moves beyond the ports 30. There is provided communication therebetween through the space between the reduced section 10 of the shaft and the secondary bore 7.

The piston 2 may be integral with the shaft 9 or suitably fixedly mounted thereon as by splines, keys. or the like, and the piston 2 is positioned intermediate the section 10 of reduced diameter and the piston 2 has an exterior surface 31 slidably engageable with the interior surface of the valve member 11. The piston 2 is effective to separate the bore 3 into respective chambers on opposite sides thereof and the piston 2 has a stroke between opposite faces 29' of the end portions 29 of the end closure portions 5 and 6.

The valve member 11 is illustrated as an elongated tubular member having opposite end portions 32 and 33 adapted to be received within the respective recesses defined by the space between the end portions 29 and the respective ends of the bore 3. The valve member 11 has a plurality of circumferentiaily spaced inlet ports 34 and 35 in the end portions 32 and 33 respectively. The valve members it is movable to alternately align the inlet ports 34 in the valve member 11 with the inlet port 17 and the annular passage 19 in the housing 4 and to align the inlet ports 35 with the inlet port 18 and the annular passage 20 in the housing 4 to provide alternate communication of fluid under pressure to opposite sides of the piston 2. The tubular valve member 11 has an exterior surface slidably engaging the interior surface of the bore 3 and the exterior surface of the tubular valve member 11 has a recess 36 therein which communicates with one of the inlet ports 34 and a recess 37 which communicates with one of the inlet ports 35 for limited flow to the annular groove or recess 28' and passages 28" in the adjacent end member 29.

The opposite end portions 32 and 33 of the valve member 11 each have a wall thickness less than a wall thickness of an intermediate portion of the valve member 11 thereby defining shoulders 38 and 39 respectively, for a purpose as later described, and the shoulders 38 and 39 are positioned adjacent the inlet ports 34 and 35 respectively. The valve member 11 has a first plurality of outlet ports 40 adjacent and spaced from the inlet ports 34 and a second plurality of outlet ports 41 adjacent and spaced from the inlet ports 35. The outlet ports 40 and 41 are alternately alignable with the outlet ports 21 and annular passage 23 and the outlet ports 41 are alignable with the outlet ports 22 and the annular passage 24. In operating a reciprocating fluid motor constructed as illustrated and described, a suitable fluid under pressure is introduced through the inlet boss 14 into the fluid intake passage 12 and flows therefrom into the bore 3 through one of the inlet ports 34 or 35 of the valve member 11. For example, when the fluid flows from the fluid intake passage 12 through the inlet port 17 and the annular passage 19 to enter the inlet ports 34 and flow into the bore 3 on one side of the piston 2 to thereby effect movement of the piston 2 away from one of the end closure portions and toward the other end closure portion. When the exterior surface 31 of the piston 2 has been moved to a position in closing relation with the outlet ports 40 adjacent the other end closure portion, fluid trapped between the piston 2 and the adjacent end closure portion has the pressure thereon increased whereby pressure on the respective shoulder 38 adjacent the respective opposite end portion of the valve member 11 effects movement of said opposite end portion away from the adjacent end closure portion whereby fluid flows from the respective secondary bore and through the flow passages 30 to thereby increase the fluid pressure on the respective end portion of the valve member I] thereby effecting movement of the valve member 11 toward the other end of the bore 3 and aligning the other inlet ports in the valve member 11 with the other inlet port and annular passage in the housing 4 so that fluid flows into the bore 3 on the opposite side of the piston 2 and pressure thereof moves the piston 2 which moves toward the other end of the bore. As the piston 2 is closing the outlet ports 40 adjacent one of the end closure portions the respective section of reduced diameter of the shaft begins to register with the flow passages in the respective end closure member. The fluid trapped between the piston 2 and the adjacent end closure portion flows through the flow passages 30 in the respective end closure portion and through the respective small flow passage 25 or 26 and into the outlet fluid passage 16 to thereby permit a limited rate of escape of the trapped fluid and to permit the piston 2 to complete its respective stroke while the valve member ll is moving in a direction opposite the direction of movement of the piston 2 and when the valve member 11 has moved. the piston 2 is moved in the opposite direction by fluid pressure entering the bore 3 through the inlet ports just opened by the valve member 1]. When the fluid motor I is stopped and the shaft 9 and the piston thereon move to either extreme position adjacent one end of the stroke of the piston 2, the fluid motor I is adapted to be self-starting as by moving the valve member H to permit fluid pressure flow between the piston 2 and the adjacent end closure portion. Fluid under pressure flows from the passage 12 through one of the inlet ports l7 and 18 to a respective annular passage 19 and 20. The flow is then into one of the recesses 36 or 37 in the exterior surface of the valve member 11 and then to the respective adjacent inlet port 34 and 3S and through the annular groove 28' and passages 28" to the secondary bore 7 to apply fluid pressure to the valve shoulder 38 and end portion of the valve member thereby effecting sufficient movement of the valve member to permit flow through the respective inlet ports and flow through the respective secondary bore and the flow passages 30 to effect fluid pressure on the end of the respective opposite end portion thereby effecting movement of the valve member and increased flow of fluid between the piston 2 and the respective adjacent end closure portion.

FIGS. 9 and 10 illustrate another feature of the invention in the form of a modified reciprocating fluid motor 45 having a housing 46 and an end closure portion 47 at one end thereof and similar to the end closure portions 5 and 6. The other end of the housing 46 has a housing extension 48 mounted thereon with a closure portion 49 extending into one end of a bore 50 and the portion extending into the bore 50 is substantially similar to the projecting portions 28 and the end portions 29 of the end closure portions 5 and 6.

The housing 46 of the fluid motor 45 is substantially similar to the housing 4 of the fluid motor 1 except that the housing 46 has a fluid intake passage 51 and a fluid outlet passage 52 each having one end thereof comm unicating with one end of the housing 46. The housing extension 48 has a fluid intake passage 53 aligned with and communicating with the fluid intake passage 51 in the housing 46 and a fluid outlet passage 54 in the form of an enlarged chamber therein adapted to receive one end of a shaft 55 having a piston 56 mounted on a section of reduced diameter intermediate the ends thereof.

One end of the housing extension 48 has a threaded opening adapted to receive an elongated outer tubular member 57 and the other end of the extension 48 has an outlet port 58 communicating with the fluid outlet passage 54 and adapted to receive one end of an inner tubular member 59.

A dual fluid passage coupling is secured to the other or outer end of the outer tubular member 57 and the inner tubular member 59 and has passages 61 and 62 therethrough with the passage 61 being adapted to communicate with a passage defined by a space between the outer tubular member 57 and the inner tubular member 59. The passage 62 communicates with the other end of the inner tubular member 59. The coupling 60 has a suitable source of fluid pressure, such as a hydraulic pump (not shown), connected to the passages 61 and 62 thereof for operation of the fluid motor 45.

The outer or free end of the shaft 55 has a suitable tool mounted thereon, such as a pavement breaker, hammer, reciprocating mower blade, saw, or other suitable tool which operates with a reciprocating motion. In the illustrated structure, a tamper foot 63 is secured to the end of the shaft 55 and is adapted to compact loose earth upon actuation by the piston 56.

Operation of the fluid motor 45 is substantially similar to operation of the fluid motor I and the movements of the piston 56 and a valve member 64 within the bore 50 is substantially similar to operation of the valve member 11, however, only one end of the shaft 55 extends from the housing 46.

It is to be understood that while we have illustrated and described certain forms of my invention, it is not to be limited to these specific forms or arrangement of parts herein described and shown.

What we claim and desire to secure by Letters Patent l. A fluid motor comprising:

a. a housing having a longitudinally extending bore therein, said housing having end closure members thereon and each having a secondary bore of reduced size therein;

b. a piston reciprocable in said bore and having elongated shafts extending therefrom and into said secondary bores, said shafts having sections of reduced diameter adjacent said piston; said piston separating the bore into respective chambers on opposite sides thereof, said piston having a stroke extending between opposite ends of said bore;

c. fluid inlet passages and fluid outlet passages and having an inlet passage and an outlet passage communicating with each of said chambers;

d. valve means having opposite end portions with end facing surfaces and being reciprocable in said bore and alternately movable in response to fluid pressure, said valve means being movable between a first position and a second position, said valve means in said first position communicating said respective inlet passage with one chamber while communicating the other chamber with said respective outlet passage thereby effecting move-' ment of said piston in one direction, said valve means in said second position communicating said respective inlet passage with the other chamber while communicating the one chamber with said respective outlet passage thereby effecting movement of said piston in the opposite direction;

e. means in each of said closure members and said housing for communicating a space defined by the respective secondary bores and the section of reduced diameter of said shafts with said outlet passage for restricted flow thereto when the piston is adjacent to and moving toward the respective closure member;

f. means operative in response to said reduced diameter shaft section entering a respective secondary bore to communicate fluid pressure from one of said inlet passages flow greater than said restricted flow to the outlet passage. said flow from said inlet passage being operative to apply force to the adjacent end facing surface of the valve means to effect movement thereof toward its other position.

2. A fluid motor as set forth in claim 1 wherein:

a. said end closure members each have a recess therein adapted to slidably receive a respective end of said valve means therein; and

b. said means for communicating each space between the respective secondary bore and the section of reduced diameter of said shaft with said outlet passage include a plurality of spaced flow passages in each of said ends closure members each communicating the respective secondary bore with said recess in the closure member and at least one flow passage for each secondary bore communicating each of said recesses with said outlet passage for said restricted flow thereto.

3. A fluid motor as set forth in claim I wherein said means communicating fluid pressure to the valve means end facing surface includes:

a. said valve means has a plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers;

b. said valve means has an exterior surface having at least one recess therein adjacent each of the opposite ends of said valve means;

c. each of said recesses communicates with a respective one of said inlet ports;

d. a passage in said closure member communicating the said one inlet port with the respective secondary bore for flow of fluid pressure thereto whereby said fluid pressure acts on a valve means end facing surface to effect movement of said valve means to its other position as the piston completes its respective stroke.

4. A fluid motor as set forth in claim I wherein:

a. said valve means has a first and a second plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers;

b. said valve means has a first and a second plurality of spaced outlet ports alternately alignable with the respective outlet passage for each of said chambers;

c. said piston alternately closes said first and second plurality of outlet ports when adjacent respective ends of the piston stroke;

d. said end closure members each have a recess therein adapted to slidably receive a respective end of said valve means therein; and

c. said means for communicating each space between the respective secondary bore and the section of reduced diameter of said shaft with said outlet passage includes a plurality of spaced flow passages in each of said end closure members each communicating the respective secondary bore with said recess in the closure member and at least one flow passage for each secondary bore for restricted communication of each of said recesses with said outlet passage with fluid pressure in the recess acting on the valve means ends to move same to its other position.

5. A fluid motor as set forth in claim 1 wherein:

a. said end closure members each have a recess therein adapted to slidably receive a respective end of said valve means therein;

b. said means for communicating each space between the respective secondary bore and the section of reduced diameter of said shaft with said outlet passage includes a plurality of spaced flow passages in each of said end closure members and each communicating the respective secondary bore with said recess in the closure member and at least one flow passage for each secondary bore for restricted communication of each of said recesses with said outlet passage;

0. said means communicating fluid pressure to the valvemeans end facing surface includes said valve means having a first and a second plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers; said valve means having an exterior surface having at least one recess therein adjacent each of the opposite ends of said valve means; each of said recesses in the exterior surface of said valve means communicates with a respective one of said inlet ports; a passage communicating the said one inlet port with the respective secondary bore for flow of fluid pressure thereto whereby said fluid pressure acts on the valve means end facing surface to effect movement of said valve means to its other position as the piston completes its respective stroke.

6. A fluid motor comprising:

a. a housing having a longitudinally extending bore therein;

b. means at each end of said bore for closing same and having a secondary bore therein, each secondary bore having a diameter smaller than said bore in said housing;

c. an elongated shaft reciprocable in said bore and said secondary bores, said shaft having spaced sections of reduced diameter intermediate the ends of said shaft;

d. a piston on said shaft and positioned intermediate the sections of reduced diameter and separating the bore into respective chambers on opposite sides thereof, said piston having a stroke extending between opposite ends of said bore;

e. fluid inlet passages and fluid outlet passages in said housing, each of said chambers having a respective inlet passage communicating therewith adjacent the respective end of the bore and a respective outlet passage communicating therewith and spaced from the respective inlet passage and the respective end of the bore;

f. valve means having opposite ends with end facing surfaces and being reciprocable in said bore and having said piston reciprocable in said valve means, said valve means being alternately movable between a first position and a second position, said valve means in said first position communicating said respective inlet passage with one chamber while communicating the other chamber with said respective outlet passage for fluid pressure effecting movement of said piston in one direction, said valve means in said second position communicating said respective inlet passage with the other chamber while communicating the one chamber with said respective outlet passage for fluid pressure effecting movement of said piston in the opposite direction;

g. a recess in each of said means for closing each end of said bore, said recesses each being adapted to slidably receive a respective end of said valve means there; and

h. means to provide communication for fluid to each space between the respective secondary bore and the section of reduced diameter of said shaft and the respective end of the valve means as said piston closes the respective outlet passage;

i. means providing restricted communication between the respective ends of the valve means and the outlet passage whereby the pressure flow to said space is greater than the escaping pressure flow and is effective to assure full reversing movement of said valve means.

7. A fluid motor as set forth in claim 6 wherein:

a. said valve means comprises an elongated tubular member having a first and a second plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers and a first and a second plurality of spaced outlet ports alternately alignable with the respective outlet passage for each of said chambers;

b. said valve means has an exterior surface having at least one recess therein adjacent each of the opposite ends of said tubular member with each of said recesses communicating with a respective one of each said inlet ports of each of said first and said second plurality of inlet ports;

c. a passage in said closure means communicating said one inlet port with the respective secondary bore for flow of fluid pressure thereto whereby fluid pressure acts on said valve means end surfaces applying force to effect movement of said valve means to its second position as the piston completes its respective stroke.

8. A fluid motor as set forth in claim 7 wherein said means to provide communication for fluid between each space between the respective secondary bore and the section of reduced diameter of said shaft and said outlet passage as said piston closes the respective outlet passage includes:

a. a plurality of spaced flow passages in each of said means for closing each end of said bore and each communicating the respective secondary bore and recess therein; and

b. at least one flow passage for each secondary bore and communicating a respective one of said recesses with said respective outlet passage said at least one flow passage having less flow capacity than the passage in the closure means.

9. A fluid motor as set forth in claim 8 wherein:

a. said piston has an exterior surface slidably engageable with an interior surface of said valve member and alternately movable to close the first and the second plurality of spaced outlet ports; and

b. said sections of reduced diameter of said shaft each have a length such that as said piston is closing one of the first and second plurality of spaced outlet ports the respective section of reduced diameter of said shaft moves to register with the plurality of spaced flow passages in the respective means for closing the respective end of said bore.

10. A fluid motor as set forth in claim 8 wherein:

a. said means for closing each end of said bore comprises an end closure member for each end of said bore and having an end surface in facing relation with said piston;

b. said valve member end facing surfaces includes a shoulder adjacent each end thereof and in facing relation with a respective end surface of the adjacent end closure member; and

c. said piston has an exterior surface slidably engageable with an interior surface of said valve member and alternately movable to close the first and second plurality of spaced outlet ports whereby fluid is trapped between said piston and the end surface of the adjacent end closure member to increase fluid pressure on the respective shoulder of the valve member for effecting movement of the valve member in a direction opposite to the direction of movement of the piston after the piston closes the respective outlet ports. 

1. A fluid motor comprising: a. a housing having a longitudinally extending bore therein, said housing having end closure members thereon and each having a secondary bore of reduced size therein; b. a piston reciprocable in said bore and having elongated shafts extending therefrom and into said secondary bores, said shafts having sections of reduced diameter adjacent said piston; said piston separating the bore into respective chambers on opposite sides thereof, said piston having a stroke extending between opposite ends of said bore; c. fluid inlet passages and fluid outlet passages and having an inlet passage and an outlet passage communicating with each of said chambers; d. valve means having opposite end portions with end facing surfaces and being reciprocable in said bore and alternately movable in response to fluid pressure, said valve means being movable between a first position and a second position, said valve means in said first position communicating said respective inlet passage with one chamber while communicating the other chamber with said respective outlet passage thereby effecting movement of said piston in one direction, said valve means in said second position communicating said respective inLet passage with the other chamber while communicating the one chamber with said respective outlet passage thereby effecting movement of said piston in the opposite direction; e. means in each of said closure members and said housing for communicating a space defined by the respective secondary bores and the section of reduced diameter of said shafts with said outlet passage for restricted flow thereto when the piston is adjacent to and moving toward the respective closure member; f. means operative in response to said reduced diameter shaft section entering a respective secondary bore to communicate fluid pressure from one of said inlet passages flow greater than said restricted flow to the outlet passage, said flow from said inlet passage being operative to apply force to the adjacent end facing surface of the valve means to effect movement thereof toward its other position.
 2. A fluid motor as set forth in claim 1 wherein: a. said end closure members each have a recess therein adapted to slidably receive a respective end of said valve means therein; and b. said means for communicating each space between the respective secondary bore and the section of reduced diameter of said shaft with said outlet passage include a plurality of spaced flow passages in each of said ends closure members each communicating the respective secondary bore with said recess in the closure member and at least one flow passage for each secondary bore communicating each of said recesses with said outlet passage for said restricted flow thereto.
 3. A fluid motor as set forth in claim 1 wherein said means communicating fluid pressure to the valve means end facing surface includes: a. said valve means has a plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers; b. said valve means has an exterior surface having at least one recess therein adjacent each of the opposite ends of said valve means; c. each of said recesses communicates with a respective one of said inlet ports; d. a passage in said closure member communicating the said one inlet port with the respective secondary bore for flow of fluid pressure thereto whereby said fluid pressure acts on a valve means end facing surface to effect movement of said valve means to its other position as the piston completes its respective stroke.
 4. A fluid motor as set forth in claim 1 wherein: a. said valve means has a first and a second plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers; b. said valve means has a first and a second plurality of spaced outlet ports alternately alignable with the respective outlet passage for each of said chambers; c. said piston alternately closes said first and second plurality of outlet ports when adjacent respective ends of the piston stroke; d. said end closure members each have a recess therein adapted to slidably receive a respective end of said valve means therein; and e. said means for communicating each space between the respective secondary bore and the section of reduced diameter of said shaft with said outlet passage includes a plurality of spaced flow passages in each of said end closure members each communicating the respective secondary bore with said recess in the closure member and at least one flow passage for each secondary bore for restricted communication of each of said recesses with said outlet passage with fluid pressure in the recess acting on the valve means ends to move same to its other position.
 5. A fluid motor as set forth in claim 1 wherein: a. said end closure members each have a recess therein adapted to slidably receive a respective end of said valve means therein; b. said means for communicating each space between the respective secondary bore and the section of reduced diameter of said shaft with said outlet passage includes a plurality of spaced flow passages in each of said end closure members and each communicating the respective secondary bore with said recess in the closure member and at least one flow passage for each secondary bore for restricted communication of each of said recesses with said outlet passage; c. said means communicating fluid pressure to the valve means end facing surface includes said valve means having a first and a second plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers; said valve means having an exterior surface having at least one recess therein adjacent each of the opposite ends of said valve means; each of said recesses in the exterior surface of said valve means communicates with a respective one of said inlet ports; a passage communicating the said one inlet port with the respective secondary bore for flow of fluid pressure thereto whereby said fluid pressure acts on the valve means end facing surface to effect movement of said valve means to its other position as the piston completes its respective stroke.
 6. A fluid motor comprising: a. a housing having a longitudinally extending bore therein; b. means at each end of said bore for closing same and having a secondary bore therein, each secondary bore having a diameter smaller than said bore in said housing; c. an elongated shaft reciprocable in said bore and said secondary bores, said shaft having spaced sections of reduced diameter intermediate the ends of said shaft; d. a piston on said shaft and positioned intermediate the sections of reduced diameter and separating the bore into respective chambers on opposite sides thereof, said piston having a stroke extending between opposite ends of said bore; e. fluid inlet passages and fluid outlet passages in said housing, each of said chambers having a respective inlet passage communicating therewith adjacent the respective end of the bore and a respective outlet passage communicating therewith and spaced from the respective inlet passage and the respective end of the bore; f. valve means having opposite ends with end facing surfaces and being reciprocable in said bore and having said piston reciprocable in said valve means, said valve means being alternately movable between a first position and a second position, said valve means in said first position communicating said respective inlet passage with one chamber while communicating the other chamber with said respective outlet passage for fluid pressure effecting movement of said piston in one direction, said valve means in said second position communicating said respective inlet passage with the other chamber while communicating the one chamber with said respective outlet passage for fluid pressure effecting movement of said piston in the opposite direction; g. a recess in each of said means for closing each end of said bore, said recesses each being adapted to slidably receive a respective end of said valve means there; and h. means to provide communication for fluid to each space between the respective secondary bore and the section of reduced diameter of said shaft and the respective end of the valve means as said piston closes the respective outlet passage; i. means providing restricted communication between the respective ends of the valve means and the outlet passage whereby the pressure flow to said space is greater than the escaping pressure flow and is effective to assure full reversing movement of said valve means.
 7. A fluid motor as set forth in claim 6 wherein: a. said valve means comprises an elongated tubular member having a first and a second plurality of spaced inlet ports alternately alignable with the respective inlet passage for each of said chambers and a first and a second plurality of spaced outlet ports alternately alignable with the respective outlet passage for each of said chambers; b. said valve means has an exterior surface having at least one recess therein adjacent each of the opposite ends of said tubulAr member with each of said recesses communicating with a respective one of each said inlet ports of each of said first and said second plurality of inlet ports; c. a passage in said closure means communicating said one inlet port with the respective secondary bore for flow of fluid pressure thereto whereby fluid pressure acts on said valve means end surfaces applying force to effect movement of said valve means to its second position as the piston completes its respective stroke.
 8. A fluid motor as set forth in claim 7 wherein said means to provide communication for fluid between each space between the respective secondary bore and the section of reduced diameter of said shaft and said outlet passage as said piston closes the respective outlet passage includes: a. a plurality of spaced flow passages in each of said means for closing each end of said bore and each communicating the respective secondary bore and recess therein; and b. at least one flow passage for each secondary bore and communicating a respective one of said recesses with said respective outlet passage said at least one flow passage having less flow capacity than the passage in the closure means.
 9. A fluid motor as set forth in claim 8 wherein: a. said piston has an exterior surface slidably engageable with an interior surface of said valve member and alternately movable to close the first and the second plurality of spaced outlet ports; and b. said sections of reduced diameter of said shaft each have a length such that as said piston is closing one of the first and second plurality of spaced outlet ports the respective section of reduced diameter of said shaft moves to register with the plurality of spaced flow passages in the respective means for closing the respective end of said bore.
 10. A fluid motor as set forth in claim 8 wherein: a. said means for closing each end of said bore comprises an end closure member for each end of said bore and having an end surface in facing relation with said piston; b. said valve member end facing surfaces includes a shoulder adjacent each end thereof and in facing relation with a respective end surface of the adjacent end closure member; and c. said piston has an exterior surface slidably engageable with an interior surface of said valve member and alternately movable to close the first and second plurality of spaced outlet ports whereby fluid is trapped between said piston and the end surface of the adjacent end closure member to increase fluid pressure on the respective shoulder of the valve member for effecting movement of the valve member in a direction opposite to the direction of movement of the piston after the piston closes the respective outlet ports. 